Polysaccharide microcrystals reinforced amorphous poly(beta-hydroxyoctanoate) nanocomposite materials

In a previous work [Macromolecules 1998, 31, 6426] the preparation techniqu e of a latex of poly(beta-hydroxyoctanoate) (PHO) obtained from Pseudomonas oleovorans grown at high cell density on sodium octanoate was presented. T he resulting films displayed typical properties of thermoplastic elastomer. Depending on the experimental purification conditions, fully amorphous PHO films can be obtained. Nanocomposite materials were prepared using this la tex as a matrix and using a colloidal suspension of hydrolyzed starch or ce llulose whiskers as a natural and biodegradable filler. After stirring, the preparations were either cast and evaporated or freeze-dried and molded. H igh-performance materials were obtained from these systems, preserving the natural character of PHO. The resulting properties were strongly related to the aspect ratio L/d (L being the length and d the diameter) of the filler and to the geometric and mechanical percolation effects. In addition, spec ific polymer-filler interactions and geometrical constraint due to the part icle size of the latex have to be considered to account for the mechanical reinforcement effect of cellulose whiskers.